Sökning: "Lavar"

Visar resultat 6 - 10 av 12 avhandlingar innehållade ordet Lavar.

1. 6. Anatomy and taxonomy of cetrarioid lichens

   Författare :Arne Thell; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; taxonomi; chemotaxonomy. Physiology of nonvascular plants; phytogeography; morphology; taxonomy; Systematic botany; pycnoconidia; ascus structures; anatomy; Systematisk botanik; cetrarioid lichens; Ascomycotina; Parmeliaceae; morfologi; kemotaxonomi. Växters fysiologi inte kärlväxter .;

   Sammanfattning : The anatomy of the cetrarioid lichens (Parmeliaceae) has been studied, and the taxonomy revised. Special attention has been paid to reproductive structures, in particular the asci and pycnoconidia. Two types of asci are recognized. The Cetraria type is narrowly clavate, bears an amyloid ring structure in the tholus, and has a small axial body. LÄS MER

3. 7. Modeling lichen performance in relation to climate : scaling from thalli to landscapes

   Författare :Anna V Jonsson Čabrajić; Kristin Palmqvist; Jon Moen; Per-Anders Esseen; Mikaell Ottosson-Löfvenius; Göran Ågren; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Lichen; growth; model; micro-climate; hydration; activation; photosynthesis; respiration; Terrestrial ecology; Terrestisk ekologi; ekologisk botanik; Ecological Botany;

   Sammanfattning : Lichens can colonize nearly all terrestrial habitats on earth and are functionally important in many ecosystems. Being poikilohydric, their active growth periods are restricted to periods when the thallus is hydrated from atmospheric water sources, such as rain, fog and high relative humidity. LÄS MER

4. 8. Plants go with the flow : predicting spatial distribution of plant species in the boreal forest

   Författare :Ursula Zinko; Christer Nilsson; Håkan Rydin; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; boreal forest; vascular plant; species richness; wetness index; soil pH; bryophyte; lichen; substrate; stand age; plot size; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi; ekologisk botanik; Ecological Botany;

   Sammanfattning : The main objectives of this thesis are to study if a topographic wetness index (TWI) could be used as a tool for predicting the spatial distribution of vascular plant species richness in the boreal forest as well as to study congruence in species richness between vascular plants, liverworts, mosses and lichens. A wetness index ln(a/tanβ) based on topography was used to assign a specific TWI-value to every 20 x 20m grid in two 25 km2 boreal forest landscapes (differing in average soil pH) in northern Sweden. LÄS MER

5. 9. Effects of enhanced ultraviolet-B radiation on subarctic ecosystems

   Författare :Carola Gehrke; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; pigmentation; photosynthesis; dark respiration; shoot morphology; shoot growth; phanerogams ; species composition cryptogams; productivity; decomposition; dwarf shrubs; bryophytes; peatland ecosystem; heath ecosystem; UV-B; ozone depletion; Plant ecology; Växtekologi;

   Sammanfattning : Biologically harmful ultraviolet-B radiation (UV-B, 280-320 nm) is increasing at the Earth´s surface owing to stratospheric ozone depletion. This is of global concern due to potential impacts of enhanced UV-B radiation on the biosphere. LÄS MER

7. 10. Activity concentrations of radionuclides in energy production from peat, wood chips and straw

   Författare :Robert Hedvall; Kärnfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Radionuclides; peat; wood; chips; straw; bioenergy; biomass; district heating; emission; Cs; Physics; Chernobyl; Radioactivity; Fysik; Technological sciences; Teknik; Fysicumarkivet A:1997:Hedvall;

   Sammanfattning : In this thesis quantitative analyses of radionuclide concentrations in bioenergy fuels such as peat, wood chips and straw are presented. For comparison a brief description is included of radionuclide concentrations and radiation doses from other sources of power and also from some industrial applications. LÄS MER